JPH11276343A - Electromagnetic induction heating type rice cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the contact area of a temperature sensor so as to accurately detect a temperature, to cook rice without errors by accurate heating control and to prevent the sink of a sink cabinet from being scratched by at least the lowest end face of the outer side bottom surface part of an inner pot in the rice cooker provided with the temperature sensor for detecting the temperature of the inner pot on the center part of the outer side bottom surface for which a magnetic metal is thermally sprayed to the outer side face of an inner pot main body formed of a non- magnetic metal. SOLUTION: This rice cooker is composed by providing the inner pot 1 and an electromagnetic induction heating coil for making the inner pot 1 generate heat inside a main body, providing the temperature sensor for detecting the temperature of the inner pot 1 by being abutted to the center part of outer side bottom surface of the inner pot 1, forming the inner pot main body 1a for constituting the inner pot 1 by a non-magnetic metal and thermally spraying a magnetic metal to the outer side face of the inner pot main body 1a. At least the lowest end face of the outer side bottom surface part of the inner pot 1 and the projection part tip of the thermal spray surface of the magnetic metal 1a of the center part of the outer side bottom surface to which the temperature sensor is abutted are smoothly finished by polishing or the like and finished to a smooth surface 1ab.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rice cooker for cooking rice by generating heat in an inner pot by electromagnetic induction heating, and more particularly, to spraying a magnetic metal material onto the outer surface of an inner pot body made of a non-magnetic metal material. The present invention relates to an electromagnetic induction heating type rice cooker.

[0002]

2. Description of the Related Art Conventional electromagnetic induction heating type rice cookers are known in which an inner pot is formed by pressing a clad material in which an aluminum plate as a non-magnetic metal material and a stainless steel plate as a magnetic metal material are pressed. A stainless steel plate, which is a magnetic metal material, is spread on the bottom of a pan-shaped receiving mold, and molten aluminum, which is a non-magnetic metal material, is poured on top of it. In addition, there has been a method in which a magnetic metal material such as iron is thermally sprayed on an outer surface of an aluminum inner pan formed by pressing or melt forging.

[0003] Among these methods, the first one has a drawback that the magnetic metal material is limited to a stainless steel plate and iron, which is a strong magnetic substance, cannot be used, so that the heat generation efficiency is poor. The whole pot is made up of aluminum and stainless steel plates of uniform thickness, so it becomes heavy,
Moreover, when processing into a complicated pot shape, there is a disadvantage that the joint between the aluminum plate and the stainless steel plate is easily peeled off.

In addition, the following high-pressure melt-forging method has the drawback that the production cost is so large that it cannot be provided to consumers inexpensively. In addition, since the stainless steel plate, which is a heating element, has a uniform thickness, electromagnetic induction is not used. It is not possible to adjust the heat generation balance by varying the thickness of the heating element according to the heating coil. Further, since the inner pan is formed by pressing the molten aluminum at a high pressure with a pressing die, the pot itself cannot be manufactured unless it has a certain thickness, and there is a disadvantage that the inner pan becomes inevitably heavy.

[0005] On the other hand, in the case of spraying a magnetic metal material on the inner pot of the nonmagnetic metal material shown last, a ferromagnetic material such as iron can be used as a heating element for induction heating. Since the magnetic material can be sprayed only on the part necessary for induction heating, the inner pan does not become unnecessarily heavy, and the thickness of the spray is variable according to the magnetic field generation condition (shape of the electromagnetic induction heating coil). This has the advantage that the heat generation balance can be adjusted.

Japanese Patent No. 2705083 is known as an electromagnetic induction heating type rice cooker using an inner pot of this thermal spraying system. JP-A-60-35491, JP-A-61-176089, JP-A-62-69481 and the like are already known.

[0007] However, those described above still cannot sufficiently exhibit the above-mentioned advantages, and have the following problems.

[0008]

That is, the above-mentioned conventional thermal spraying method is a method in which a magnetic metal material is melted into fine particles, and the fine particles are sprayed at a high pressure onto the outer surface of an inner pot to make close contact. The magnetic metal material layer is formed to a desired thickness by stacking fine particles in multiple layers. For this reason, the outer surface of the inner pot after thermal spraying has a file-like shape due to the lamination of fine particles, and the outer surface has been subjected to a process to give a beautiful appearance by a rust prevention layer or a fluororesin layer etc. .

However, the file-like irregularities are not filled with a rust preventive layer or a fluororesin layer. Therefore, there is no particular problem when used as a pot for an electromagnetic cooker. When used as a pot, a temperature sensor is in contact with the center of the outside bottom of the inner pot, and based on the temperature information from it, appropriate heat control, so-called "starting chorochoro, middle papa ..." Occurs. That is, when the inner pan is inserted into the main body, the temperature sensor is caught by the unevenness, and the temperature sensor becomes oblique and does not abut parallel to the center of the outer bottom surface of the inner pan, or even if it abuts parallel, it contacts with the unevenness There were problems such as an unstable area. For this reason, the temperature of the temperature sensor became low as the contact area was small, despite the high temperature of the inner pot, and there was a problem that the rice could not be cooked properly or could not be cooked deliciously without being able to control the heat properly. .

[0010] In addition, in a rice cooker, it is common to grind rice with a sink or the like in a sink, and the outermost lower end surface of an inner pot in contact with a stainless plate or the like of the sink has a file-like shape. However, there was a problem that the sink was scratched when polishing rice.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made to further improve the above-mentioned thermal spraying method, in which a magnetic metal material is thermally sprayed on the outer surface of an inner pot body made of a non-magnetic metal material. In addition, at least the lowermost end of the outer bottom surface and the tip of the file-like convex portion of the sprayed surface at the center of the outer bottom surface in contact with the temperature sensor are smooth-finished by a method such as polishing to provide a smooth surface, This prevents the temperature sensor from getting caught and tilting when the inner pan is inserted,
The contact area is stable, accurate temperature detection is possible, and accurate fire control enables cooked rice to be cooked without loss.
No damage to the sink when polishing rice.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to an inner pot, an electromagnetic induction heating coil for heating the inner pot, and a temperature sensor for detecting the temperature of the inner pot by contacting the center of the outer bottom surface of the inner pot. And a rice cooker in which the inner pot body constituting the inner pot is formed of a non-magnetic metal material, and a magnetic metal material is sprayed on an outer surface of the inner pot body. At least the thermal sprayed surface of the magnetic metal material at the center of the outer bottom surface where the lowermost surface contacts the temperature sensor is finished to a smooth surface.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a rice cooker according to the present invention in a front-rear direction. FIG. 2 is a cross-sectional view in the left-right direction of the rice cooker. FIG. 3 is an enlarged view of the bottom portion of the inner pot of the rice cooker. FIG. 3A is an enlarged view of a case where a sprayed surface is not formed as a smooth surface, and FIG.

1 is an inner pot, 2 is a main body, 3 is a lid, 4
Is a protective frame, 5 is an electromagnetic induction heating coil, 6 is a temperature sensor, 7 is a control unit, 8 is a magnetic shield, 1a is an inner pot body, 1b is a magnetic metal material, 1c boundary, 1d is a rust prevention layer, and 1e is The fluororesin layer, 1f is a thick portion at the upper portion of the inner pot, 1g is a flange portion, and 1h is a handle of the inner pot 1.

More specifically, the inner pan 1 is housed in the main body 2 so as to be detachable, and a lid 3 is attached to the main body 2 so as to be openable and closable, and the upper openings of the inner pan 1 and the main body 2 are closed. doing. A protective frame 4 is provided inside the main body 2,
An electromagnetic induction heating coil 5 is provided at the bottom of the protection frame 4. The electromagnetic induction heating coil 5 is formed by winding an electric wire a plurality of times in the circumferential direction, and does not exist at or near the center of the bottom of the inner pan 1, but from near the middle of the bottom radius of the inner pan 1 to the bottom corner. The inner pan 1 is integrally provided in a flat plate shape up to a point farther from the electromagnetic induction heating coil 5, that is, in the vicinity of the diameter of the upper end of the inner pan 1. A temperature sensor 6 is provided at the center of the bottom of the protective frame 4 and is in contact with the center of the outer bottom surface of the inner pot 1.

A control section 7 for generating a high-frequency magnetic field in the electromagnetic induction heating coil 5 is provided in the main body 2, and a temperature sensor 6 is also connected to the control section 7 so as to generate electric power determined based on temperature information. The energization of the electromagnetic induction heating coil 5 is controlled. A magnetic shield 8 is provided on the lower surface of the electromagnetic induction heating coil 5.
Is provided to absorb the lower magnetic field of the high-frequency magnetic field generated vertically from the electromagnetic induction heating coil 5 and generate the magnetic field only on the upper side where the inner pot 1 is located.

The inner pan 1 is made of aluminum, which is a high heat conductive material, is formed into a pan shape by pressing or molten metal forging, and is subjected to a roughening process on the outer surface to increase the adhesion of thermal spraying. And a magnetic metal material 1b such as iron formed on the bottom by thermal spraying.
b indicates that the bottom surface facing the electromagnetic induction heating coil 5 has a thickness of 0.
The inner pot 1 is formed to have a thickness of about 7 mm, and is gradually thinned from the corner to the side of the inner pot 1 so that the thickness becomes zero at the boundary 1c. Further, the thickness of the bottom portion facing the electromagnetic induction heating coil 5 is gradually reduced from the thickness of 0.7 mm to the center, and the thickness of the contact portion of the temperature sensor 6 at the center is about 0.4 mm. It is formed as follows. The thermal spraying is a method in which the magnetic metal material 1b is melted and sprayed into the inner pot main body 1a at a high pressure in the form of fine particles and adhered to each other. Is formed. Therefore, the thickness can be easily varied as described above by adjusting the range to be sprayed and the time for spraying (generally, adjusting the program of the movement of the robot arm).

As shown in FIG. 3A, the sprayed surface of the magnetic metal material 1b has a file-like shape due to lamination of fine particles. In the present invention, the magnetic metal material 1 at least at the lowermost end surface of the outer bottom surface of the inner pot 1a and the center of the outer bottom surface where the temperature sensor 6 abuts among the file-shaped irregularities.
As shown in FIG. 3 (b), the convex portion 1aa of the b is polished and finished to a smooth surface 1ab, and a rust prevention layer 1d is formed on the smooth surface 1ab.
Is formed by thermal spraying. The rust preventive layer 1d is made of a material such as zinc or aluminum for the purpose of preventing rust of the magnetic metal material 1b, and has a thickness of about 0.05 mm which is substantially uniform. The range is provided so as to completely cover the magnetic metal material 1b in a range wider than the magnetic metal material 1b. This rust-preventing layer 1d is also produced by thermal spraying. However, since the particles are finer and thinner than the magnetic metal material 1b, they are formed along the shape of the surface of the magnetic metal material 1b without forming file-like irregularities. You. Further, the entire outer surface of the inner pot 1 is covered with a fluororesin layer 1e from above.

At the upper end of the inner pot 1, there is formed a thick portion 1f and a flange portion 1g formed by folding an aluminum material or by forming a thicker portion than other portions by a molten metal forging method. The thick portion 1f has a heat storage effect by being thicker than the other portions, stores heat during cooking, and keeps the upper end of the inner pot 1 that is exposed from the protective frame 4 and cools down to a high temperature even when steamed. Like that.

Further, an inner pot handle 1h is provided on the flange portion 1g at two opposing positions in the left-right direction. The handle 1h is installed on the main body 2 and the inner pot 1 is fixed. It is held in a state where it does not touch d.

Next, the operation will be described along the flow of rice cooking.

First, a user puts a desired amount of rice into the inner pot 1 and then rinses the rice with a sink. At this time, since the rice is sharpened with force, the bottom surface of the inner pot 1 is laterally shifted and rotated while being pressed against the sink. However, in the present invention, since the outermost lowermost surface of the inner pot 1 in contact with the sink is the smooth surface 1ab, the sink is not damaged.

After the washing of rice is completed, an appropriate amount of water is put into the inner pot 1 and a rice cooker switch (not shown) is operated.
Starts cooking rice. A high-frequency current flows from the control unit 7 to the electromagnetic induction heating coil 5, thereby generating a high-frequency magnetic field from the electromagnetic induction heating coil 5. Since the downward magnetic field is absorbed by the magnetic shielding material 8, a magnetic field is generated only on the upper side of the inner pot 1 side. The generated high-frequency magnetic field passes through the fluororesin layer 1e and the rust-preventive layer 11d of the inner pot 1 on which magnetism does not act, acts on the magnetic metal material 1b, and is converted into heat. This heat is transmitted from the magnetic metal material 1b to the inner pot main body 1a, and is transmitted to the entire bottom face and side faces of the inner pot 1 due to the high thermal conductivity of the inner pot main body 1a, and is also transmitted to the rice and water in the inner pot 1 for rice cooking. In this embodiment, since iron is used for the magnetic metal material 1b, it is a ferromagnetic material as compared with stainless steel or the like, has a high efficiency of converting a magnetic field into heat, and can heat the inner pot 1 with strong thermal power. Even if iron is used for the magnetic metal material 1b, the boundary 1c
Since it is protected by the rust prevention layer 1d provided above and the fluororesin layer 1e provided on the entire outer surface of the inner pot 1, it does not rust.

On the other hand, the central portion of the inner pot 1 is strongly affected by the heat conducted through the thickness of the inner pot main body 1a and the temperature of water and rice in the inner pot 1. At this time, the temperature sensor 6 in contact with the center of the inner pot 1 receives heat from the bottom surface of the inner pot 1 and detects the temperature, but is also affected by the ambient temperature in the main body 1, in other words, the room temperature. Therefore, when the contact area with the bottom surface of the inner pot 1 decreases, there is a characteristic that a lower temperature is detected with respect to the bottom surface. Therefore, if the temperature sensor 6 is caught on the bottom surface when the inner pan 1 is inserted, the temperature sensor 6 tilts and the contact area is significantly reduced, or even if the temperature sensor 6 does not tilt, the contact area becomes unstable if the bottom surface has irregularities. However, in the present invention, since the contact surface of the temperature sensor 6 of the inner pot 1 is also a smooth surface 1ab, the contact is stable,
The temperature of the inner pot 1 can be detected without being affected by the surroundings, and the rice can be cooked deliciously by accurate fire control.

By this accurate temperature detection, the control of the program of the control unit 7 executes the control of the so-called "starting chorochoro, middle pupper ...", and controls the energization of the electromagnetic induction heating coil 5 to advance the rice cooking. .

When the inside of the inner pot 1 boils over time, the lid 3
Thick part 1 of inner pan 1 due to excess heat of steam discharged from
The heat is stored in f and reaches approximately 100 ° C. When the rice sucks the water in the inner pan 1 and the water runs out, the temperature at the bottom in the inner pan 1 rises rapidly, the temperature sensor 6 catches this, finishes the rice cooking, and shifts to steaming.

During the steaming, the cooked rice in the inner pot 1 is kept at a high temperature and steamed by the heat stored in the inner pot body 1a and the heat stored in the thick portion 1f. In particular, the temperature of the upper end of the inner pot 1 exposed from the protection frame 4 tends to decrease, but in the present embodiment, since the heat is stored in the thick portion 1f, the temperature decrease is small and a sufficient steaming effect can be obtained. After the steaming for a certain period of time, rice is ready and ready to be eaten.

After the rice is eaten, the inner pot 1 is washed, but in the present invention, the sponge or the like is not caught by the smooth surface 1ab and can be cleaned cleanly.

[0029]

As described above, according to the present invention, the inner pan is formed of a non-magnetic metal material, and the outer surface of the inner pan is sprayed with the magnetic metal material. Since the end surface and the contact surface of the temperature sensor were formed with a smooth surface that finished the tip of the convex part smoothly by a method such as polishing,
The temperature sensor does not get caught and tilted when the inner pot is inserted, and the contact area is stable, so accurate temperature detection is possible, which enables accurate fire control, and cooks delicious rice without missing cooking .

Further, since the lowermost end surface of the outer bottom portion, which is in contact with the inner pot when the inner pot is placed on the sink, is also finished to a smooth surface, it is not damaged by the file-like projections.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rice cooker according to the present invention in a front-rear direction.

FIG. 2 is a cross-sectional view in the left-right direction of the rice cooker.

FIG. 3 is an enlarged sectional view of a bottom portion of an inner pot of the rice cooker, in which (a) is a case where a smooth surface is not formed as it is sprayed, and (b) is a diagram where a smooth surface is formed.

[Explanation of symbols]

 Reference Signs List 1 inner pot 1a inner pot main body 1ab smooth surface 1b magnetic metal material 2 main body 5 electromagnetic induction heating coil 6 temperature sensor 7 controller

Claims (1)

[Claims] 1. An inner pot (1) in a main body (2), an electromagnetic induction heating coil (5) for heating the inner pot (1), and an outer bottom center of the inner pot (1) in contact with the inner pot. A temperature sensor (6) for detecting the temperature of the inner pot (1) is provided, and the inner pot body (1a) constituting the inner pot (1) is formed of a non-magnetic metal material. In the rice cooker obtained by spraying the magnetic metal material (1b) on the outer surface of the inner pot (1), at least the lowermost surface of the outer bottom surface of the inner pot (1) and the center of the outer bottom surface in contact with the temperature sensor (6). Metal material (1
An electromagnetic induction heating type rice cooker in which the sprayed surface of b) is finished to a smooth surface (1ab).